Manual electronic keyboard



Sept. 2, 1969 s. R. HERR ETAL 3,464,531

MANUAL ELECTRONIC KEYBOARD Filed May 16, 1967 INVENTORS, EDWARD R. HERR a GEORGE E SUMRALL M BMW? AT TORNE Y8 United States Patent 3,464,531 MANUAL ELECTRONIC KEYBOARD Edward R. Herr, Lakewood, and George E. Sumrall,

Neptune, NJ., assignors to the United States of America as represented by the Secretary of the Army Filed May 16, 1967, Ser. No. 640,442 Int. Cl. B41j /08, 5/16; H01v 7/00 US. Cl. 197-98 2 Claims ABSTRACT OF THE DISCLOSURE Background of the invention The present invention relates to a manual information input device and more particularly to electronic keyboards.

In the field of automatic data processing it has been the general practice to use manual keyboards which employ complicated mechanical levers, sliding bars, and other sundry gadgets which may work scatisfactorily in the controlled environment such as found in offices but fail rather quickly when exposed to the elements of a military environment.

It is, therefore, an object of the present invention to provide an electronic keyboard which is relatively immune to the effects of temperature, humidity, shock, dust, etc.

Another object is to provide an electronic keyboard which will operate in a manner which will impose no restrictions on the standard typist or his techniques.

A further object of the invention is the provision of an electronic keyboard which will be relatively quiet when being operated.

Brief description of the drawings Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawing in which like reference characters designate like or corresponding parts throughout the figures thereof and wherein:

FIGURE 1 shows a schematic diagram of the electronic keyboard;

' FIGURES 2 and 3 show isometric views in section with parts broken away of two alternative forms of a portion of the invention shown in FIGURE 1; and

FIGURES 4 and 5 show circuit diagrams of two alternative forms of a portion of the invention shown in FIG- URE 1.

Description of the preferred embodiments Referring now to the drawing, wherein like reference characters designate like or corresponding parts throughout the several views, there is shown in FIGURE 1 an electronic keyboard having a mounting plate 11 and a plurality of receptacles 12 distributed in any desired fashion. A plug-in sensing key 13 is inserted in each receptacle 12. Key 13 has a pair of contact plugs 14 and 15 which contact a pair of conductors 16' extending from each of the receptacles 12 to an amplifier circiut 17. The

3,464,531 Patented Sept. 2, 1969 ice output of amplifiers 17 are connected to a coding circuit 18, such as a diode matrix, which has a plurality of output terminals 19. A flexible cover 20 is mounted on each key 13 and is arranged to be depressed by the fingers of an operator. The amplifiers 17 will detect the operation of the associated key and transmit a signal to the coder 18 thereby producing a coded output on lines 19.

FIGURES 2 and 3 show two variations of the keys 13. The key 13 of FIGURE 2 includes a cylindrical housing 26 having removable top and bottom walls 21 and 22 respectively. Top wall 21 has an opening 23 for the reception of the plunger 24. Plunger 24 consists of a twopiece cylindrical shaft portion 25 and a circular cap portion 29. The bottom portion 38 of shaft 25 is screwed into the top portion 39 to provide a circumferential groove 27 for the reception of a steel leaf spring 28. Spring 28 is substantially rectangular in shape and has a central open- 1ng 31 to fit into groove 27 of shaft 25. A pair of grooves 35 in the interior surface of housing 26 is provided for the reception of the curved ends 30 of spring 28.

Bottom wall 22 has centrally located thereon an electromechanical transducer 32. Transducer 32 should preferably be of durable material which is relatively immune to the effects of temperature, humidity, dust, etc. Most standard piezoelectric and piezoresistive materials meet these limitations. A pair of conductive contacts 33 and 34 are mounted on opposite sides of the transducer 32. A pair of conductive plugs 14 and 15 extend through wall 22. Plug 14 is connected to contact 34 and cover 22 and will be used as the ground terminal. Plug 15 is connected to contact 33 and is insualted from cover 22 by a dielectric bushing 37. A flexible cover 20 is placed over cap 29 and mm intimate contact with the exterior of housing 26. The flexible cover 20 provides a finger engaging surface for the operator and a seal for protection of the interior of housing 26 from dust, moisture, etc.

The key 13 of FIGURE 2 is arranged to operate in the compression mode such that upon compression of transducer 32 a signal is generated on lines 16. FIGURE 3 shows a modification wherein the transducer 32 is mounted to operate in a bending mode. In FIGURE 3 the key 13 includes a plunger 24 havmg a cap 29 and a shaft 25 extending through an opening 23 in the top wall 21 of the housing 26. The interior of housing 26 includes a pair of opposed grooves 35. The ends of a pair of leaf springs 40 and 41 are inserted in grooves 35'. Springs 40 and 41 are made of conductive material. The ends of spring 40 are covered with an insulating material 42 and the ends of spring 41 are in contact with the conductive housing 26. An electro-mechanical transducer 32 is sandwiched between the springs 40 and 41. A pair of contact plugs 14 and 15 which extend through the bottom wall 22 are connected to springs 40 and 41 respectively. Plug 14 is in contact with the wall 22 and plug 15 is insulated from wall 22 by a dielectric bushing 37. A flexible cover 20 covers cap 29" and extends over housing 26 and into intimate contact therewith.

In the device of FIGURE 3, upon depression of plunger 24 by an operator the transducer 32 will be flexed by the curved end portion 43 of plunger 24'. In the case where the transducer 32 is a piezoelectric crystal a voltage will be developed between plugs 14 and 15 due to the bending of the transducer 32. A change in resistance between plugs 14 and 15 will be produced by the bending of a piezoresistive transducer.

FIGURES 4 and 5 show circuit diagrams of the amplifiers 17 and the modification 17 respectively and the relationship of the transducer in the circuit. The transducer 32 of FIGURE 4 would be of a piezoresistive type and is one side of a voltage divider circuit which includes transducer 32 and resistor 45. The base electrode of transistor 46 is connected through a high impedance resistor 50 to the midpoint 47 of the divider so that transistor 46 will be normally in the off condition. With a change in the resistance of transducer 32, due to the operation of the key 13, current will flow through transistor 46 and bias resistor 48. Terminal 49 will therefore show a change in voltage which will be coded by coder 18.

A piezoresistive transducer 32 may also form one leg of a balanced bridge the output of which could be applied to a transistor 46 for amplification and application to coder 18.

The circuit of FIGURE shows a piezoelectric transducer 32' applied through a high impedance resistor 50 to the base of a transistor 51 for amplification of a voltage produced across transducer 32'. The output terminal 52 of transistor 51 is to be applied to coder 18.

These amplifiers 17 and 17' could be located in the output lines 19 thereby reducing substantially the number of amplifiers. Of course, the outputs of the keys 13 would have to be of a suflicient amplitude to drive the coder 18.

What is claimed is:

1. A manually operated electronic key comprising a housing; electromechanical transducer means mounted in said housing; a pair of conductive terminals extending from one side of said housing; conductive means for connecting said terminals to said transducer means; said transducer means having crystal means for providing an electrical signal at said terminals upon mechanical deformation of said crystal means; said housing having an opening on the side opposite said one side; a plunger upon movement of said plunger toward said crystal having a shaft and a cap mounted on one end of said shaft; said plunger being slidably mounted in said opening with said one end protruding from said housing and the other end of said shaft extending towards said crystal means; the length of said shaft being greater than the distance from said crystal means to said opening; a leaf spring means having two spaced leaves mounted in said housing for providing a restoring force to said plunger upon movement of said plunger toward said crystal means; said crystal means being sandwiched between and in-contact with said leaves; and said leaf spring means being mounted in a plane transverse to the direction of motion of said plunger and with opposite ends thereof lying in slots formed in the walls of said housing.

2. The device according to claim 1 further including a flexible cup means extending over said cap and into frictional contact with the outside walls of said housing; and said cap being in contact with said cup means and said other end of said shaft being in contact with said leaf spring means.

References Cited UNITED STATES PATENTS 2,032,168 2/1936 Degen.

2,302,081 11/1942 Weitmann 3108.5 X 3,076,903 2/1963 Schwartz 310-8.3 3,353,038 11/1967 Mason et al. 310-8.3 X 3,364,451 1/1968 Paul et al. 3108.7 X 3,366,808 1/1968 Steward 3108.5 X 3,333,122 7/1967 Christian 310-9.1 3,339,104 8/1967 Kushner et al. 310-91 X OTHER REFERENCES IBM Technical Disclosure Bulletin, Piezoelectric Crystal Keyboard, J. J. Sharp, vol. 5, No. 10, March 1963, p. 95.

ERNEST T. WRIGHT, JR., Primary Examiner US. Cl. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,464,531 September 2, 1969 Edward R. Herr et al.

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 32, "scatisfactorily" should read satisfactorily Column 3, line 32, cancel "upon movement of said plunger toward said crystal".

Signed and sealed this 21st day of April 1970.

(SEAL) Attest:

Edward M. Fletcher, Jr.

Attesting Officer Commissioner of Patents WILLIAM SCHUYLER, JR. 

